class?UrlManager(object):
????#?管理器要維護(hù)待爬取的和爬去過的兩個(gè)URL列表
????def?__int__(self):
????????self.new_urls?=?set()
????????self.old_urls?=?set()
????def?add_new_url(self,url):??#向管理器中添加一個(gè)url
????????if?url?is?None:
????????????return
????????if?url?not?in?self.new_urls?and?url?not?in?self.old_urls:
????????????self.new_urls.add(url)

哪位大神幫忙看下？用的是python3.6